[8833] | 1 | /* Definitions for condition code handling in final.c and output routines. |
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| 2 | Copyright (C) 1987 Free Software Foundation, Inc. |
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| 3 | |
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| 4 | This file is part of GNU CC. |
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| 5 | |
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| 6 | GNU CC is free software; you can redistribute it and/or modify |
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| 7 | it under the terms of the GNU General Public License as published by |
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| 8 | the Free Software Foundation; either version 2, or (at your option) |
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| 9 | any later version. |
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| 10 | |
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| 11 | GNU CC is distributed in the hope that it will be useful, |
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 14 | GNU General Public License for more details. |
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| 15 | |
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| 16 | You should have received a copy of the GNU General Public License |
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| 17 | along with GNU CC; see the file COPYING. If not, write to |
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| 18 | the Free Software Foundation, 59 Temple Place - Suite 330, |
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| 19 | Boston, MA 02111-1307, USA. */ |
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| 20 | |
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| 21 | /* None of the things in the files exist if we don't use CC0. */ |
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| 22 | |
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| 23 | #ifdef HAVE_cc0 |
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| 24 | |
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| 25 | /* The variable cc_status says how to interpret the condition code. |
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| 26 | It is set by output routines for an instruction that sets the cc's |
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| 27 | and examined by output routines for jump instructions. |
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| 28 | |
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| 29 | cc_status contains two components named `value1' and `value2' |
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| 30 | that record two equivalent expressions for the values that the |
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| 31 | condition codes were set from. (Either or both may be null if |
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| 32 | there is no useful expression to record.) These fields are |
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| 33 | used for eliminating redundant test and compare instructions |
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| 34 | in the cases where the condition codes were already set by the |
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| 35 | previous instruction. |
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| 36 | |
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| 37 | cc_status.flags contains flags which say that the condition codes |
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| 38 | were set in a nonstandard manner. The output of jump instructions |
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| 39 | uses these flags to compensate and produce the standard result |
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| 40 | with the nonstandard condition codes. Standard flags are defined here. |
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| 41 | The tm.h file can also define other machine-dependent flags. |
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| 42 | |
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| 43 | cc_status also contains a machine-dependent component `mdep' |
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| 44 | whose type, `CC_STATUS_MDEP', may be defined as a macro in the |
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| 45 | tm.h file. */ |
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| 46 | |
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| 47 | #ifndef CC_STATUS_MDEP |
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| 48 | #define CC_STATUS_MDEP int |
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| 49 | #endif |
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| 50 | |
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| 51 | #ifndef CC_STATUS_MDEP_INIT |
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| 52 | #define CC_STATUS_MDEP_INIT 0 |
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| 53 | #endif |
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| 54 | |
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| 55 | typedef struct {int flags; rtx value1, value2; CC_STATUS_MDEP mdep;} CC_STATUS; |
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| 56 | |
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| 57 | /* While outputting an insn as assembler code, |
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| 58 | this is the status BEFORE that insn. */ |
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| 59 | extern CC_STATUS cc_prev_status; |
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| 60 | |
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| 61 | /* While outputting an insn as assembler code, |
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| 62 | this is being altered to the status AFTER that insn. */ |
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| 63 | extern CC_STATUS cc_status; |
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| 64 | |
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| 65 | /* These are the machine-independent flags: */ |
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| 66 | |
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| 67 | /* Set if the sign of the cc value is inverted: |
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| 68 | output a following jump-if-less as a jump-if-greater, etc. */ |
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| 69 | #define CC_REVERSED 1 |
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| 70 | |
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| 71 | /* This bit means that the current setting of the N bit is bogus |
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| 72 | and conditional jumps should use the Z bit in its place. |
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| 73 | This state obtains when an extraction of a signed single-bit field |
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| 74 | or an arithmetic shift right of a byte by 7 bits |
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| 75 | is turned into a btst, because btst does not set the N bit. */ |
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| 76 | #define CC_NOT_POSITIVE 2 |
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| 77 | |
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| 78 | /* This bit means that the current setting of the N bit is bogus |
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| 79 | and conditional jumps should pretend that the N bit is clear. |
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| 80 | Used after extraction of an unsigned bit |
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| 81 | or logical shift right of a byte by 7 bits is turned into a btst. |
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| 82 | The btst does not alter the N bit, but the result of that shift |
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| 83 | or extract is never negative. */ |
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| 84 | #define CC_NOT_NEGATIVE 4 |
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| 85 | |
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| 86 | /* This bit means that the current setting of the overflow flag |
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| 87 | is bogus and conditional jumps should pretend there is no overflow. */ |
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| 88 | #define CC_NO_OVERFLOW 010 |
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| 89 | |
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| 90 | /* This bit means that what ought to be in the Z bit |
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| 91 | should be tested as the complement of the N bit. */ |
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| 92 | #define CC_Z_IN_NOT_N 020 |
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| 93 | |
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| 94 | /* This bit means that what ought to be in the Z bit |
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| 95 | should be tested as the N bit. */ |
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| 96 | #define CC_Z_IN_N 040 |
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| 97 | |
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| 98 | /* Nonzero if we must invert the sense of the following branch, i.e. |
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| 99 | change EQ to NE. This is not safe for IEEE floating point operations! |
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| 100 | It is intended for use only when a combination of arithmetic |
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| 101 | or logical insns can leave the condition codes set in a fortuitous |
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| 102 | (though inverted) state. */ |
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| 103 | #define CC_INVERTED 0100 |
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| 104 | |
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| 105 | /* Nonzero if we must convert signed condition operators to unsigned. |
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| 106 | This is only used by machine description files. */ |
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| 107 | #define CC_NOT_SIGNED 0200 |
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| 108 | |
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| 109 | /* This is how to initialize the variable cc_status. |
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| 110 | final does this at appropriate moments. */ |
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| 111 | |
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| 112 | #define CC_STATUS_INIT \ |
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| 113 | (cc_status.flags = 0, cc_status.value1 = 0, cc_status.value2 = 0, \ |
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| 114 | CC_STATUS_MDEP_INIT) |
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| 115 | |
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| 116 | #endif |
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